Protective device



Jan. 16, 1951 E. KOLISCH PROTECTIVE DEVICE i Filed April '30, 1948 6! 5T 13 52 6.6 54 10? slimy INVENTOR Emzl Kolzscfl/ ATTORNEYS Patented Jan.16, 1951" PROTECTIVE DEVICE Emil Kolisch, New York, N. Y., assignor toContinental Silver (10., Inc., Brooklyn, N. Y., a corporation of NewYork Application April so, 1948, Serial No. 24,233

12 Claims. 1

This invention relates to protective devices, more especially forelectrical appliances of the type used in the home or in the oflices ofphysicians and "dentists and particularly to a device which breaks thecircuit when the appliance is overheated and may be readily reset tooperativeness and, though applicable to heaters for water, liquids orfluids generally, such as for sterilization or for culinary purposes, isshown herein applied to a coffee percolator.

It is among the objects of the invention to provide a protective devicefor an electrical heating appliance of the above type which is ofsimple, relatively inexpensive, compact and rugged construction, whichdoes not detract from the normal operation of the appliance, which isnot exposed to contact with the materials to be heated by the applianceand which yet may be completely concealed from the exterior of theappliance, which .will function to interrupt the circuit uponoverheating of the appliance as for instance, in the absence of desiredliquid therein, which functions without appreciable arcing both inmaintaining the circuit in use and in interrupting the circuitupon'overheating, and which admits of being instantly and unerringlyrestored to operativeness by the unskilled user by resort to a simplemanipulation, such as the turn of a knob accessible from the exterior ofthe appliance and without the need for any tools for disassembly;

or for reaching into the interior of the device.

It is a feature of the invention to provide a plurality of fusible linksof which one only is maintained. in operative position Where it issubjected to the heat evolved in the appliance, the remaining fusiblelinks being in reserve for ready replacement upon fusing and rupture ofthe link'in use under excessive heat. To this end the fusible link inaction is in engagement with a stop or contact in effectiveheatconducting and circuit closing relationship with the heating elementof the appliance. The stop and the fusible link are relativelydisplaceable, preferably by a manual member accessible from theexterior,

such as for instance from the bottom of the appliance, for readilyreplacing a fused link with a reserve link. Preferably each link ismounted on a support and the stop has associated therewith a resilientmember which, when the link engages the stop is stressed, thereby toforce the stop against the link to exert pressure thereagainst, so thatupon softening of the fusible link in action under excessive heat, thelatter will readily be ruptured to sever the link and causedisengagement from the stop thereby to 2 break the circuit. In apreferredconstruction, the fusible links radiatefrom a rotatable mountwhich desirably rises from the bottom of the device and to which isaflixed the manually operated knob, while the stop is aflixed thereabovewith its associated resilient member.

Another feature of the invention is the provision of means on therotatable mount to enable it to rotate only in one direction, therebyensuring that the link will properly engage the stop so that positiveelectric contact will be made.

This application is a continuation in part of my copending application,Serial No. 767,696, filed August 9, 1947. i

In the accompanying drawings in which are shown one or more of variouspossible embodiments of the several features of the invention,

Fig. 1 is a longitudinal cross sectional view of the electricalappliance with parts broken away, Fig. 2 is a transverse cross sectionalview taken along line 22 of Fig. 1,

Fig. 3 is a longitudinal cross sectional viewtaken along line 33 of Fig.1,

Fig. 4 is a detail perspective view on a larger scale of the fusiblelink and support therefor, and Fig. 5 is a bottom view of the heaterhousing. Referring now to the drawings there is shown a preferredembodiment of the protective device as applied to a coffee percolatorII]. The latter comprises a container ll affixed as by welding as at I2,to a hollow base [3 which has an annular flange I4 at the bottom.thereof affixed to the bottom rim l5 of the base by rivets IS. A bottomplate I! is affixed to said flange l4 by means of screws l8 which alsomount legs l9 and which pass through the bottom plate I! and arethreaded into corresponding openings 2| in the flange l4. v

Carried by the top 25 of the base l3 and extending through an opening 26therein is a generally cylindrical, preferably ceramic mount 21. Acylindrical protective housing 28 encompasses that portion of the mountwhich protrudes above top 25 and has an inturned rim 29 extending underdiametrically opposed laterally extending ears 3i integral with themount 21. .To permit assembly of the housing 28 to the mount, the rim 29may have diametrically opposed slots 32 to accommodate said ears 3| sothat upon slight rotation of the housing 28, after introduction of theears into the slots 32, the housing is attached relative to the mount. Anut 33 secured upon the threaded lower end 34 of the mount 21 causes theears 3| to be pressed against the 3 inturned rim 29 of the housing,rigidly to clamp the housing and the mount to the base.

A high resistance wire is wound around the upper end 36 of the mount 21which is of slightly reduced diameter forming an annular ledge 31. Oneend 98 of the wire is connected to the head of a bolt 39 which extendsthrough a bore M in the ledge 31 and the mount 21', and protrudes fromthe bottom of the mount as at 42, being retained therein by a nut 43.The other end 44 of the resistance wire 35 passes through a bore 45 inthe ledge 31 and mount 2l and extends from the bottom of the mount as at4B and is connected by a lead 41 to a terminal plug 48 rigidly aiiixedto the Wall of the base 53 and insulated therefrom by insulating washers49, as is the companion terminal plug 5|.

The protective device disposed within the hol low base l3 establishes anelectric circuit from the two'ends 38 and '44 of the heating coil to thetwo terminals 48 and 5!, respectively. lhe device includes a pluralityof fusible links 54, each carried by a corresponding support 55. Anelectrical contact closes circuit to one only of said links. The ruptureof the fusible link under excessive heat results in automaticinterruption of the electric circuit, preferably under release of stressresilientl imposed in operative position. The contact and the fusiblelinks are then relatively displaceable by manual action to restore thecircuit. It is, of course, not necessary that-the entire length of thelink be of fusible material but only a portion thereof need be in orderto break the circuit when such fusible portion ruptures.

The embodiment of the protective device herein chosen to illustrate myinvention comprises a substantially L-shaped bracket 55 of heatconducting metal such as sheet metal, having laterally extending ears5'! and 51' on the side edges respectively of its downwardly extendingarm 58 and with its transverse arm 59 exten ing at substantially rightangles to arm 58 and afflxedto-the bottom end 42 of bolt 39 by nut 43,as shown in Fig, 3.

Pivotally'mounted on arm 58, as by a nut 6i and' bolt 92, is a stop orcontact preferably in the form of a metal finger 53 having a laterallyprojecting hook 64 at the end thereof. By means of a tensed spring 95about bolt 62 which coacts atone end with ear 51, as at 6B, and at itsother end with the rear edge of finger 63, as at the finger is normallyurged about the pivot toward ear 5T which limits rotation of saidfinger.

Mounted within the base on the upper face ll of'a substantially circularflat domed portion 12 formed in the bottom plate i3, is a substantiallyU-shaped bracket (4, having laterally extending arms 15 which areafiixed to face 7! by rivets 16. Extending through an opening H in thecross piece 78 of bracket 14, and through an axial opening 19 in theface ll of the bottom plate !3, is a shaft 8! having a flange B2integral therewith and seated on the cross piece '59. A collar 83 isaffixed on shaft 8| beneath cross piece 18 by a set screw 84 securely,yet rotatably to support the shaft on bracket 14.

Carried on the shaft is a mount 80 comprising a disc 85 of insulatingmaterial mounted at its axis on the upper part 86 of shaft 8!, as is agenerally circular metal contact plate 81 positioned on said disc 85 andwhich has a hub 88 of insulating material through which said upp r part189 extends.

Plate Bl has a plurality of radiating slots 99,

therethrough illustratively six in number, through each of which extendthe arms 89 of the substantially L-shaped bracket or support 55, base 92of which extends at right angles to arms 59 and is sandwiched betweendisc and plate 87, and in electrical contact with the latter. By meansof a nut 93 threaded on the end 86 of shaft 8|, the plate and disc aretightly clamped together against flange 82, thereby rigidly clamping thebases 92 of supports 55 therebetween, securely to retain arms 99 inupright position.

In order to provide a convenient means for rotating the mount 89 fromthe exterior of the base, the end of the shaft 9| which extends throughopening 79 in the bottom plate has a knob 95 affixed thereon by a setscrew 96, the legs 19 of the base and the dome l2 affording clearancefor said knob when the appliance I9 is placed on a table.

The upper ends of each pair of arms 89 are bent over a fusible link 54securely to hold the latter parallel to and radially of the plate 81 andaligned with the contact finger 63 so that the latter will be in thesubstantially circular path of the links and when the mount is rotated,

the links will successively abut against said contact finger.

Also affixed on face TI is an L-shaped bracket 93, the upstanding arm 99of which has affixed thereto an insulating block l9l, which carries alaterally extending resilient contact arm I92 affixed thereon by screwsI93 and which is in electrical contact at its free end I94 with the rimof contact plate Bl. In order to limit the rotation of mount 80 to onedirection only, the rim of the plate 87 is provided with a plurality ofratchet teeth I95 which coact with the end 94 of contact arm I92 urgedthereagainst by reason of the resiliency of said arm and which functionsas a ratchet pawl.

In order to complete the electrical circuit, screw I93 is connected bylead 10'! to terminal 5! on the wall of the base. 1

With a link 54 against stop 63, as shown in Figs. 1, 2 and 3, thecontainer II is filled with liquid and a source of current is applied toterminal plugs 48 and 5|. The circuit is from terminal plug 48, lead 41,heating element 35, bolt 39, bracket 59, stop finger 63, link 54,support 55, metal carrier plate 81, contact arm I02 and lead 19? toterminal 5|. Since a good heat conducting path is established from thesource of heat to the stop finger 93, overheating (as for instance inthe absence of liquid) will cause the engaged link 54 to soften. Beforethe fusible link melts, its mechanical strength will have been sogreatly reduced that the tension of the spring urged stop finger 63 willexert sufficient pressure against the link quickly to shear the latter,as the stop finger 63 rotates on its pivot thereby breaking the circuitso rapidly that there is no danger of arcing.

But for this mechanical shearing action, if the user should cut off theelectric current when the fusible link had just begun to soften and hadbeen deformed from its original shape, it would remain in this deformedcondition when the apparatus was permitted to cool to normaltemperature. The deformity of the link might cause only slight contactto be made between the link and the stop finger 63, resulting in a highresistance joint which, upon passage of current therethrough uponfurther use of the appliance,

might cause sufiicient heat to develop at the' point of contact to meltthe link even though the container was full of water and the applianceoperating normally.

As the links other than the one in operation, are not in contact withany heat conducting metal such as the stop 63, although the tempera turein the base will rise due to overheating in container H, this rise willnot be sufficient to weaken them before the circuit is broken by therupture of the link in operative position.

ihe user, noticing that the device is not operating, will turn knob 95to again complete the heating circuit. As the link that formerly hadbeen against stop finger 63 has been sheared, there is nothing to impedethe counter-clockwise rotation of the knob 95, as shown in Fig. 2.

When the knob is turned in a counterclockwise direction, lin; 5 willfirst abut against the hook end (5 of the stop finger 63. As the knob isrotated further, the link will pivot the stop fin er do until the rearedge of the latter abuts against ear ill, in which position spring 65will be in highly tensed condition. It is to be noted that with stopfinger B3 exerting pressure against link 5% and the end we of contactarm m2 is in engagement with one of the teeth )5 on the periphery ofplate 3'5, a positive contact will be made between the link '54 and thestop finger 63 that will not jar loose.

Thus the device hereinabove described, an ciilcient protective device isprovided that will positively break th circuit inthe event of anyoverheating, yet can quickly and simply be adjusted to restore theappliance to operative condition without the need for special skill orany tools. I

When all the fusible links have been melted, it is a relatively simplematter to remove the bottom plate ll by unloosing screws it. The entirecarrier unit or mount 80 can then b replaced by a new unit or the plate8? can be removed from disc Ell by removing nut 93 whereupon the linkcarrying supports can be withdrawn from slots til and replaced.

As many changes could be made in the above construction, and manyapparently widely different embodiments of this invention could be madewithout departing from the scope of the claims, it is intended that allmatter contained in the above description or shown in th accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Havin thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. A. protective device for electric heating appliances, said devicecomprising a mount having a plurality) of supports thereon, a fusiblelink carried by each of said supports and extending radially of saidmount, a contact stop engaged by one of said links and maintaining thecorresponding support in circuit, means to maintain a pressure of thecontact stop at substantially right angles against the engaged linkwhereby upon weaken ng of said link, the contact stop will rupture thelatter to break the circuit, and means after rupture of said engagedlink to bring the next fusible link into engagement with said contactstop.

2. A protective device for electric heating appliances, said devicecomprising a rotatable mount, a plurality of supports rotatable withsaid mount, a fusible link carried by each of said supports and extendinradially of said mount, a contact stop of heat conducting materialengaged by one of said links and maintaining the corresponding supportin circuit, means upon Weakening of the engaged link to rupture thelatter, and means after rupture of the engaged link to bring the nextfusible link into engagement with said contact stop, said rupturingmeans exerting pressure against said link at substantially right anglesthereto.

3., A resettable protective device for electric heating appliances, saiddevice comprising a manually rotatable mount, a plurality of supportsrigid with said mount, a fusible link carried by each of said supports,a pivoted, stressed contact finger of heat conducting material engagedby one of said links and maintaining the correspondin support incircuit, and means successively to bring said links into engagement withsaid pivoted contact finger and to stress the latter, whereby uponweakening of the engaged link, the stressed finger will pivot to rupturesaid link, thereby to break the circuit.

4. A resettable protective device for electric heating appliances, saiddevice comprising a rotatable insulating disc, a generally circularcontact making element to said disc, a plurality of supports rigid withsaid. element and said disc and rotatable therewith, a -fusible link atthe end of each of said supports, a contact of heat conducting materialengaged by one of said links and maintaining the corresponding supportin circuit, stressed resilient means urging said contact against saidlink whereby upon weakening of the engaged link, the latter will beruptured and said resilient means unstressed, and means successively tobring said links into engagement with said contact and to stress saidresilient means.

5. A resettable protective device for electric heating appliances, saiddevice comprising a rotatable insulating disc, a plate aflixed to saiddisc, a plurality of radially positioned supports rigid with said plateand said disc and rotatable therewith, a fusible link carried by each ofsaid supports, a pivoted contact finger of heat conducting material inthe path of rotation of said links, engaged by one of said links andmaintaining the corresponding support in circuit, stressed resillentmeans urging said pivoted contact finger against said link, whereby uponweakening of the engaged link the latter will be ruptured and saidresilient means unstressed, and means successively to bring said linksinto engagement with said contact finger and to stress said resilientmeans.

6. A resettable protective device for electric heating appliances, saiddevice comprising a rotatable insulating disc, a generally circularmeta1 contact plate rigid with said disc and having a plurality ofradiating slots therein, a plurality of metal brackets clamped betweensaid disc and said plate and extending respectively through said slots,a fusible link at the extending end of each of said brackets, a pivotedcontact finger of heat conducting metal in the path of rotation oi saidfusible links, means resiliently urged against the rim of said carrierto make contact therewith, stressed resilient means urging said pivotedcontact finger against said link, whereby upon weakening of the engagedlink the latter will be ruptured, thereby to break the circuit andunstress said resilient means, means to rotate said disc and said plate,thereby successively to bring each of said links into contact with saidcontact finger and to stress said resilient means, and ratchet means tolimit the direction of rotation of said disc and said plate.

7. A resettable protective device for an electric heating appliance,said device comprising an insulating disc rotatably mounted on saidbottom plate, a generally circular contact making element rigid withsaid disc and rotatable therewith, a plurality of brackets rigid withsaid disc and element and rising therefrom, a fusible link on each ofsaid brackets, a contact finger in the path of rotation of said fusiblelinks, and a contact arm having its free end resiliently urged againstthe rim of said element to make contact therewith.

8. A resettable protective device for an electric heating appliance,said device comprising an insulating disc, a generally circular contactmaking plate aikixed to said disc and having a plurality of radiatingslots therein, means rigid with said disc for manually rotating saiddisc and said contact plate, a resilient arm coacting with said contactplate to limit the rotation thereof, a plurality of substantiallyL-shaped brackets clamped between said disc and said contact plate andrespectively rising upwardly through the slots in said contact plate, afusible link afilxed to the free end of each of said brackets, and apivoted contact finger in the path of rotation of said fusible linkssuccessively to engage the latter as said disc and said carrier arerotated.

9. The combination set forth in claim 8, in which said contact plate hasa plurality of ratchet teeth on the rim thereof and said resilient armhas a pawl at the end thereof in engagement with said ratchet teeth, tolimit the rotation of said contact plate.

10. A resettable protective device for an electric heating appliance,said device comprising a bracket, a depending contact finger pivoted tosaid bracket, an insulating disc, a metal contact plate afiixed to saiddisc, means rigid with said disc for manually rotating said disc andsaid contact plate, a plurality of brackets rigid With said contactplate rising upwardly therefrom, a fusible link affixed to the end ofeach of said brackets, the path of rotation of said brackets and saidlinks causing said linlis successively to abut against said contactfinger, resilient means urging said contact finger against said links,and

acontact arm having its free end urged against the rim of said contactplate.

11. A resettable protective device for electric heating appliances, saiddevice comprising a rotatable mount including an insulating disc, agenerally circular contact making element superposed thereon, meansrigidly clamping said contact element and said disc together, fuse linkcarrying elements rising from said contact element, a fusible link atthe end of each of said carrying elements, a contact of heat conductingmaterial engaged by one of said links pressing thereagainst andmaintaining the corresponding carrying elements in circuit, whereby uponweakening of the engaged link the latter will be ruptured, meanssuccessively to bring said links into engagement with said contact, saidrotatable mount having peripheral ratchet teeth and coacting pawl meansfor limiting the rotation of said mount in one direction.

12.A resettable protective device for an electric heating appliance ofthe type having a heatir element, said device comprising a rotatableinsulating disc, a generally circular metal contact plate rigid withsaid disc and having a plurality or" radiating slots therein, aplurality of brackets clamped between said disc and said plate andextending respectively through said slots, a fusible link at theextending end of each of said brackets, a contact finger of heatconducting metal in electrical circuit with said heating element and inthe path of rotation of said fusible links, means to rotate said discand said plate, thereby successively to bring each of links intocoirtact with said contact finger, and resilient means to retain saidcontact finger and said link in engagement.

EMIL KOLISCH.

Date

Murphy Jan. 5, 1932

